The invention relates generally to apparatus for mounting a rotational drive unit and, more particularly, to a lost motion mounting apparatus for interconnecting a rotational drive unit on a support track.
There are a wide variety of designs and uses for rotational drive units. A common use is to rotate threaded couplings or gear systems wherein the rotational movement produces relative motion of the rotational drive unit and the coupling or gear system. The mounting of the rotational drive unit must be capable of accommodating this relative motion. Applications which also include the translational movement of the rotational drive unit require further accommodation from the mounting apparatus.
A particular application of travelling rotational drive units is in underground tunnelling systems for advancing a boring head and associated drill string from an above-ground platform along a desired underground path. In assembling and disassembling the drill string from or into its constituent pipe sections, the rotational drive unit is reciprocally moved along a support track and rotated to thread and unthread the pipe sections. If the mounting apparatus of the rotational drive unit does not permit a range of movement of the rotational drive unit relative to the pipe section engaged by the rotational drive unit, the position of the rotational drive unit must be manually adjusted in small increments to prevent binding of the rotational drive unit, the pipe section, and the support rack.